Physical chemical and electrochemical study of the electrolyte based on bis(trifluoromethanesulfonyl)imidur 1-(2,2,2-trifluoroethyl)-3-methylimidazolium

Abstract

In seeking the electrolyte replacing the conventional electrolyte based on organic solvent, bis(trifluoromethanesulfonyl)imidur-1-(2,2,2-trifluoroethyl)-3-methylimidazolium ionic liquid was studied for using as electrolyte in lithium batteries. Bis(trifluoromethanesulfonyl)-imidur-1-(2,2,2-trifluoroethyl)-3-methylimidazo-lium was synthesized via tosylate 2,2,2-trifluoroethyl by using microwave or ultrasound irradiation. The physico-chemical and electrochemical properties including melting temperature (Tm), degradation temperature (Td), density, viscosity, ionic conductivity and electrochemical window of synthesized ILs were characterized and compared to those of commercial electrolyte and electrolytes based on imidazolium and ammonium cations. Bis(trifluoromethanesulfonyl)imidur-1-(2,2,2-trifluoroethyl)-3-methylimidazolium exhibited good thermal stability, excellent electrochemical stability in comparing to the commercial electrolyte and ammonium cation based ILs. However, the high viscosity of ILs is still an obstacle for lithium-ion batteries application. Thus, the addition with small amount of organic solvent is able to improve the viscosity, the cycling behavior without destroying the non-volatility and thermal stability of the ionic liquid.